Conventional coordinate input devices are well known in the prior art. These devices use a sensor that has a large number of loop coils arranged in x and y directions and a position indicator that includes a coil. In these coordinate input devices, a sensor detects a position indicated by the position indicator using an electromagnetic effect between the sensor and the position indicator.
The sensor used by the coordinate input device must have lines for supplying power to the respective loop coils and for extracting signals from the loop coils. In conventional devices, the lines are extracted from the loop coils toward the outside of the region where the loop coils are provided and are connected to a control circuit.
The sensor for the coordinate input device has a region that can detect a position indicated by the position indicator. This region has an area where the loop coils are provided. This region is called the “detectable area”. By contrast, the region where only the lines are provided and the sensor cannot detect the position indicated by the position indicator is called the “invalid area”.
For the coordinate input device, increasing the detectable area that can be used for the operation of the position indicator and reducing the overall size are major challenges. To address these challenges there is a need to minimize the invalid area.
For example, Japanese Patent No. 2842717, assigned to the assignee of the present invention, discloses a technology in which the lines for supplying power to the loop coils and for extracting signals from the loop coils are arranged between wires of the loop coils and are extracted to the outside of the loop coils, thereby succeeding in reducing the invalid area.
According to the sensor disclosed in Japanese Patent 2842717, the lines are efficiently extracted toward the outside of the loop coils, so that a control circuit substrate or the like can be connected to the sensor. This makes it possible to reduce the invalid area.
However, an increase in the detectable area and a reduction in the invalid area, as described above, are still major challenges.